Expansion tank install

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RVBraq

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Hey fellas,

I'm planning out an install of an expansion tank near my water heater as I've been having a lot of relief valve water discharge. I've got 1/2 inch copper tubing lines but the tank I'm looking at (Amtrol ST-5) has a 3/4 inch connection - Seems most tanks I'm finding are 3/4 inch connectors. I've been having trouble finding a T that will connect 1/2 inch pipe with a threaded 3/4 inch opening for the tank to screw into. Is there any harm in using a reducer connector on the tank that converts down into 1/2 inch before connecting it to the Tee? Or if not, any recommendations for an expansion tank for a 40 gallon heater at about 60 PSI ?
 

Terry

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I normally use brass fittings to install the expansion tank to the water heater.
3/4" brass tee
3/4" brass 90
3/4" x 6" nipple
3/4" x 2" nipple

I also don't think the reduction to 1/2" will be an issue for the expansion tank.

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Dana

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I normally use brass fittings to install the expansion tank to the water heater.
3/4" brass tee
3/4" brass 90
3/4" x 6" nipple
3/4" x 2" nipple

I also don't think the reduction to 1/2" will be an issue for the expansion tank.

When installing it off the side of a tee on a long nipple like that it's better if the weight of the tank is carried by something other than just the plumbing- that's quite a moment-arm! Otherwise weight and vibration over time can eventually fatigue the metal and break the nipple off a the tee (even without an earthquake event.)

Of course that's going to happen a lot sooner if it's half-inch pipe, and probably not at all if it's 1-1/4" pipe. A 3/4" brass solution is probably going to outlast the water heater in low-vibration installations, say on a basement or garage slab, but not necessarily if it's on a busy street with truck traffic or areas with lots of small earthquakes. With half-inch pipe it would DEFINITELY need some other mechanical support for the tank.

expansion-tank.jpg
 
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Terry

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When installing it off the side of a tee on a long nipple like that it's better if the weight of the tank is carried by something other than just the plumbing- that's quite a moment-arm! Otherwise weight and vibration over time can eventually fatigue the metal and break the nipple off a the tee (even without an earthquake event.)

In the Seattle area many of us are installing the expansion tanks this way. The fittings have been lasting longer than the water heaters.
 

Reach4

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With half-inch pipe it would DEFINITELY need some other mechanical support for the tank.
A wedge doorstop inserted under the elbow in the direction of the tee would be cheap and easy, where the expansion tank is close to the top of the WH.
 
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